LKML Archive on
help / color / mirror / Atom feed
From: David Wilder <>
To: Andrew Morton <>
Subject: Re: [PATCH 0/3] A kernel tracing interface
Date: Thu, 28 Feb 2008 11:40:21 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Andrew Morton wrote:
> On Tue, 26 Feb 2008 14:38:37 -0800 "David J. Wilder" <> wrote:
>> These patches provide a kernel tracing interface called "trace".
>> ChangeLog:
>> -Updated to 2.6.25-rc2-mm1
>> -Removed sem_watch example, to hard to maintain.
>> -Added a new example that demonstrates per-cpu continuous tracing
>>  of data generated using marker probes.
>> -Removed inline from relay patch.
>> -Moved examples into /sample directory.
>> The motivation for "trace" is to:
>> - Provide a simple set of tracing primitives that will utilize the high-
>>   performance and low-overhead of relayfs for passing traces data from
>>   kernel to user space.
>> - Provide a common user interface for managing kernel traces.
>> - Allow for binary as well as ascii trace data.
>> - Incorporate features from the systemtap runtime that are
>>   useful to others.
> So... what's the story on this versus lttng?

Trace is simpler to use and a smaller bit of code than lttng.
It may not have all the features of lttng but it is good starting point 
that can be expanded upon.  I have several users of trace that just 
wanted a simple way to get data out of the kernel without the overhead 
of lttng trace is working well for them.  Trace also works well with 
markers and kprobes.  For example systemtap is is using the basic trace 
code to gather data from kprobes and markers.
> Is there some userspace code available for people to test this?  Maybe it's
> mentioned and I missed it.

I purposely designed trace so no special user code is required to gather 
trace data. Standard user utilities like cat, grep, sort and more is all 
that is needed.  I show an example in /samples/trace/fork_trace.c.

However since trace uses relay as its transport any user interfaces 
provided by relay can be used to read trace data. (documented in 

> It'd be interesting to see a writeup of the proposed kernel<->userspace
> interfaces.  I see a description of kernel-internal interfaces, but how do
> users use it?

I will add some text in the documentation.
> I see it uses things from blktrace.  Can blktrace be switched over to being
> a client of this code?


> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to
> More majordomo info at
> Please read the FAQ at

  reply	other threads:[~2008-02-28 19:41 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-26 22:38 David J. Wilder
2008-02-28 10:04 ` Andrew Morton
2008-02-28 19:40   ` David Wilder [this message]
2008-02-29  5:36     ` K. Prasad
2008-02-29 12:08       ` K. Prasad
  -- strict thread matches above, loose matches on Subject: below --
2007-11-13  1:02 David J. Wilder
2007-10-02 18:55 David J. Wilder
2007-10-02 16:33 David J. Wilder

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \
    --subject='Re: [PATCH 0/3] A kernel tracing interface' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).